Magnetic Field-Boosted Pt Utilization in MOFs for Efficient Hydrogen Evolution Reaction

The scarcity and high cost of platinum (Pt) resources severely hinder the industrialization of hydrogen production via water electrolysis, necessitating enhanced Pt utilization while maintaining a high catalytic activity. Although metal-organic frameworks (MOFs) enable initial Pt dispersion, mass-transfer limitations during Pt reduction within MOF pores limit practical catalytic performance. This study introduced a magnetic field modulation strategy that leveraged the magnetohydrodynamic (MHD) effect during ion exchange in a ZnCo-ZIF precursor to achieve a 2.5-fold increase in Pt utilization, effectively overcoming mass-transfer limitations. The Pt-Co/NC-0.5 T catalyst prepared under a 0.5 T magnetic field exhibits excellent hydrogen evolution reaction (HER) performance in 1 M KOH electrolyte, achieving an ultralow overpotential of only 9 mV at a current density of 10 mA cm^-2, significantly outperforming Pt-Co/NC (98 mV) and commercial Pt/C (36 mV). The mass activity of Pt-Co/NC-0.5 T is 15.5-fold and 3.5-fold higher than those of Pt-Co/NC and Pt/C, respectively. Moreover, at an overpotential of 100 mV, the turnover frequency (TOF) of Pt-Co/NC-0.5 T reaches 0.387 s^-1, which is 2.7-fold that of Pt-Co/NC. This work demonstrates that magnetic fields can effectively regulate Pt mass transfer efficiency within the confined spaces of MOFs, offering a strategy for developing highly efficient hydrogen-production catalysts.